Angioplasty is the technique of mechanical widening a narrowed or totally obstructed blood vessel; typically as a result of atherosclerosis. A catheter is used to maneuver a tightly folded balloon attached to the distal end of the catheter into the narrowed location (stenosis). An incompressible fluid is then pumped through the catheter to inflate the balloon and enlarge the narrowed portion of the blood vessel. Relatively high pressures, in some instances up to 30 atmospheres, may be used to inflate the balloon. After the procedure is complete, a negative pressure may be applied through the catheter to remove the incompressible fluid, deflating the balloon for removal from the blood vessel.
Catheter dilation balloons are typically provided with a rated operating pressure and a rated burst pressure. The rated operating pressure is the pressure at which the balloon reaches its nominal diameter. The rated burst pressure is a statistical measure, e.g., typically a maximum pressure at which there is a 95% confidence level that 99.99% of balloons will not fail. Non-compliant catheter balloons are typically used at pressures between the rated operating pressure and the rated burst pressure.
However, due to the high pressures used in many cases to inflate a dilation catheter balloon during angioplasty and the relatively small volume of the balloons used, there is a potential to pressurize a dilation balloon beyond its rated burst pressure. Further, in some instances a dilation catheter balloon may be inflated and deflated multiple times during angioplasty, weakening the balloon. If a balloon bursts during angioplasty, there is a possibility that portions of the balloon may separate from the catheter, possibly necessitating surgery to remove the separated portions of the balloon from the patient's artery. Thus, there exists a need for a means of preventing over-inflation of dilation balloons during procedures such as angioplasty.